The present invention relates to a catheter intended for at least partial implantation within a living body for special or long term usage, and more particularly to a catheter having at least one unidirectional valve for controlling fluid flow into or out of the catheter.
Various medical procedures require vascular access over a period of time. Such procedures may include implantation of a permanent intravascular device for use with portable drug infusion devices, for hemodialysis, or for cases where continuous blood work or access to the bloodstream is required. These procedures are often performed by using either transcutaneous or totally implanted catheters.
It is desirable to limit the number of such devices intruding into the human body and it is also desirable to limit the possibility of infection, blood embolism and the like, by precluding diffusion of blood into the device when it is not in use.
To accomplish this, it is desirable to include a check valve integral with the catheter, so that when a pressure differential of a first sense is established across the catheter wall near its tip, a valve opens permitting fluid flow therethrough and when a pressure differential of the oppose sense is established, the valve closes and prevents fluid flow therethrough. Such check valves may be implemented to permit fluid flow either from the catheter or into the catheter.
These valved catheters, however, have multiple element valve assemblies resulting in a corresponding complexity.
A prior art catheter features a slit-type bidirectional check valve. The tip of the catheter is closed and the side wall of the catheter near the tip has a linear slit extending parallel to the central axis of the catheter, to form the slit valve. See U.S. Pat. No. 4,701,166. The valve allows both aspiration of blood and infusion of fluids depending upon the sense of the pressure differential across the catheter wall at the tip. The check valve precludes the diffusion of blood into the lumen when there is no pressure differential across the wall of the catheter. A catheter of this type is known as the Groshong catheter. While effective for some applications, this type of catheter typically has a very narrow range of pressure differentials at which no fluid flow occurs.
While various other valved catheters are also known, there is still a need for an improved, at least partially implantable, unidirectional valved catheter assembly which is easy to manufacture and easy to install in a patient, provides a distinct and reliable cut-off of reverse flow, and yet limits the possibility of infection, blood embolism, leakage and the like.
It is therefore an object of the present invention to provide an improved valved catheter which is easy to manufacture.
It is another object of the present invention to provide an improved catheter with at least one unidirectional valve.
Another object is to provide an improved bidirectionally valved catheter adapted for placement in the bloodstream.